BE1020736A3 - PROCESS FOR THE GRANULOMETRIC SEPARATION OF MATERIAL RICH IN FILIFORM PARTICLES - Google Patents

Description

"METHOD FOR THE GRANULOMETRIC SEPARATION OF MATERIALS RICH IN FILIFORM PARTICLES"

The present invention relates to a method for selectively separating a granular material comprising a bulk particle fraction and a fine particle fraction for separating said solid particle fraction from said fine particle fraction, said method comprising a feeding step of said granular material, a step of selectively separating said fraction of solid particles from said fraction of fine particles and a step of recovering said fraction of separated solid particles and said fraction of separated fine particles

Such a method is known for example from EP1712301 which discloses a method for separating filiform fragments from shredded electronic elements using an apparatus which consists of a wheel whose surface is covered by a layer of fibers (textiles) on which will hang the filiform fragments during the fall of the electronic elements crushed on the wheel. When the wheel is spinning and under the action of gravity, the elements not fixed to the fiber layer will fall into a first recovery tank while the filiform elements will fall into a second tank when they are subjected to gravity and gravity. above the second bin. This apparatus is therefore based on the fall of the shredded electronic elements, which will be driven by the wheel in the same direction as that of the falling elements.

EP726817 discloses a method and apparatus for separating filiform elements from other elements also from electronic equipment. The principle of this device is identical to that of EP1712301, with the difference that the surface of a circulating carpet is provided with bristles in which the filiform particles are fixed.

DE4117029 relates to the granulometric separation of filiform particles from a mixture of particles of various shapes and sizes. The separation of the filiform particles is based on the use of inclined conveyor belts driving the filiform particles upwards while the larger particles slide along the conveyor belts under the action of the force of gravity.

Document DE 9017891 relates to a method using a device also consisting of treadmills which are provided on their surface with bristles for fixing the filiform particles. The filiform particles are separated in the same manner as described in DE4117029, the presence of hairs here reinforcing the rise of the filiform particles at the top of the mats.

Screening methods are also known from the state of the art for the selective separation of a granular material comprising filiform particles and fine particles. Screening methods rely on the use of screens for filtering solids of different sizes.

Unfortunately, the methods of the state of the art suffer from clogging problems related to the accumulation of filiform elements, for example twisted, at the level of the fibers and the hairs of the wheels or carpets, which makes it impossible to to obtain an optimal separation of filiform elements and elements of different granulometries. These screening methods also have a relatively long residence time for efficient separation of the filiform particles. Moreover, said filiform particles constitute additional attachment points for other filiform particles, which generally complicates the operations.

The aim of the invention is to overcome the drawbacks of the state of the art by providing a method of selective separation of a granular material comprising a fraction of solid particles and a fraction of fine particles as indicated at the beginning, characterized in that said supply of said granular material is effected on a rotating circular plate having a bottom inclined with respect to a horizontal plane and a central zone for collecting said fine particles, said method also comprising simultaneously a first displacement of said solid particles in a regime cascading to a periphery of said rotating circular plate and a second displacement of said fine particles in a cataract regime towards said central collection zone of said rotary circular plate, by rotation of said rotary circular plate at a rotation speed of at least 50% but less than 100% of the speed cr rotation of said rotating circular plate, with said separation of said solid particle fraction from said fine particle fraction and said recovery of said solid particle fraction by overflow of said rotating circular plate and said fraction of fine particles separated and concentrated in said central collection zone of said rotating circular plate.

Such a method makes it possible to avoid any clogging related to the presence of filiform particles and ensures a correct separation of the fraction of solid particles from the fraction of fine particles because each of the two aforesaid fractions are respectively subjected to a particular movement of the material, which has the effect of selectively separating each of the two fractions. Indeed, provided that the rotational speed of said rotary circular plate is at least equal to 50% but less than 100% of the critical rotation speed, the mass fraction of particles undergoes a shift in a cascade while while simultaneously the fraction of fine particles is displaced by a cataract regime.

The fine particles, subjected to the cataract regime, describe trajectories passing through the center of said rotating circular plate where they concentrate.

The massive particles, subjected to the cascade regime, describe trajectories shorter than those of the fine particles and do not pass through the center of said rotary circular plate. The cascade regime causes the massive particles to fall on each other, these massive particles thus colliding. A collapse and a fallout of the massive particles on themselves is thus obtained.

In addition to the respective displacements of each of the two fractions, the granular material is also divided according to two other criteria. On the one hand, under the effect of rotation of the rotating circular plate, the granular material is pressed against the peripheral edge of said rotary circular plate and, on the other hand, the granular material is divided into several layers depending on the density particles, the finest and densest particles forming the lower layers while the more massive and less dense particles form the upper layers.

In the granular material in motion, gravity plays a role and the massive particles that are less dense supernatant on the surface of the granular material present on the turntable while the finest and densest particles form a lower layer in contact with the bottom of the rotating circular plate. These fine particles are entrained towards the center of the rotating circular plate under the effect of the rotation of said rotary circular plate and of friction forces exerted between the bottom of the rotary circular plate and said fine particles in contact with this bottom, said particles thus being subjected to training forces. These same fine particles transmit the driving forces to which they are subjected to the particles forming the upper layers, said driving forces being transmitted layer by layer to the upper layer of the granular material. A gradient of driving forces perpendicular to the bottom of the rotating circular plate is thus observed, the magnitudes of said driving forces decreasing during their transmission from one layer to the other of particles in an upward direction.

As mentioned above, the rotating circular plate having an inclined bottom, the particles are also subjected to the force of gravity. Fine particles that are dense, but small and therefore light, are not subject to the force of gravity, while heavier particles, which are less dense and more bulky, are more heavily subjected to them. the latter more quickly down. Since, as described above, the particles are subjected to driving forces, the effect of the gravitational force on the particles results in their ability to describe more or less large trajectories, the densest fine particles and the lighter ones describing larger trajectories than the heavier and less dense particles.

The distribution of the particles in different layers according to their density but also the different trajectories described by the particles according to their density and as a function of the displacement of the material (cascade or cataract) to which they are subjected makes it possible to obtain a selective separation, when the displacement of the granular material in the rotating circular plate having an inclined bottom is carried out at a speed of rotation at least equal to 50% but less than 100% of the rotational speed of said rotary circular plate. According to this particular rotational speed, the movements of the material according to the cascade and cataract regimes are obtained simultaneously surprisingly.

The massive particles supernate the surface of the granular material while the fine particles are concentrated at the bottom of the rotating circular plate in a central collection zone.

The regimes of displacement of the material in a cylinder (cataract regime, slip regime, rolling regime, centrifugal regime, subsidence regime, cascade regime) are characterized by the number of Froude (equation 1) which characterizes the importance relative forces related to the speed and the force of gravity.

where r: the radius of the cylinder [m] ω: the angular velocity [rad / sec] g: the force of gravity 9.81 [m / s2]

In the context of the present invention and for a predetermined diameter of the rotating circular plate, the number of Froude and therefore the movement rate of the material is a function of the rotational speed of the rotating circular plate. It is thus possible to define a critical rotation speed of the rotating circular plate (Ne) (equation 2) beyond which the cascade and cataract regimes are exceeded to give rise to the centrifugal regime characterized by a number of Froude equal to 1.

(Equation 2) where Ne: the critical drive speed [lat / sec] g: the force of gravity 9.81 [m / s2] β: the angle of inclination of the plate D: the diameter of the plate [m]

It has been observed, in the context of the present invention, that the more the rotating circular plate is inclined with respect to a horizontal plane, the more the installation can process and thus separate a large flow of material. Indeed, the more the rotating circular plate is inclined, the more it is necessary to increase the speed of rotation to preserve the quality of the separation. Increasing the rotation speed of the rotating circular plate has the effect of increasing the driving forces and the increase of the rotating circular plate inclination angle with respect to a horizontal plane has the effect of accentuating the effect of the force of gravity on the particles. This is why, under these conditions, the less dense particles are driven down more rapidly while the denser particles are more rapidly directed to the central collecting area of the rotating circular plate, which, therefore, accelerates the separating the particles of different particle sizes and allows the treatment of a larger flow of granular material.

For the purposes of the present invention, the term "fraction of solid particles" is intended to mean a fraction of granular material comprising filiform particles and / or coarse particles.

For the purposes of the present invention, the term "filiform particles" is intended to mean particles having a preferential direction but also corrugated portions and which can therefore be wound on themselves or intermesh with each other. This is, for example, pieces of cables.

For the purposes of the present invention, the term "coarse particles" is intended to mean particles having a size of between 0.2 and 200 mm.

For the purposes of the present invention, the term "fine particles" is intended to mean particles having a size of between 0.01 and 133 mm.

For the purposes of the present invention, the following ratio must be observed: [(coarse particle size) / (fine particle size)]> 1.5 where coarse particles mean that 80% of the coarse particles of the granular material exhibit size smaller than a size between 0.2 and 200 mm, and where dso fine particles means that 80% of the fine particles of the granular material have a size less than a size between 0.01 and 133 mm.

Advantageously, according to the method of the present invention, said rotary circular plate has, in a trigonometric marker, a first quadrant extending from 0 to 90 °, a second quadrant extending from 90 ° to 180 ° and a third quadrant. extending from 180 ° to 270 ° with respect to a point 0 corresponding to an uppermost point of said rotary circular plate when it is stationary, said filiform particles and / or said coarse particles being recovered in a peripheral collector in the form of a downward ramp fixed along at least a portion of said third quadrant of said rotary circular plate, preferably along an arc of between 180 ° and 270 °, after overflowing said rotary circular plate, said particles filiforms aggregating together in the form of balls. Such positioning of said peripheral collector ensures optimum recovery of the agglomerated filiform particles in the form of balls which, by overflow of said rotating circular plate, fall into said collector which directs them to a collection zone.

Preferably, according to the method of the present invention, said recovery of said fine particles in said central collection zone of said inclined rotary circular plate is carried out manually, preferably by suction, preferably via at least one opening made on the bottom of said central collection zone, preferably with the aid of a worm.

Advantageously, according to the process of the present invention, a separation of said coarse particles from said bonded filiform particles in the form of balls is carried out by means of a finger screen situated in the extension of said peripheral collector. The coarse particles pass through the fingers of said finger screen and are thus found in a first recovery tank while the balls remain on the surface of the finger screen and are oriented towards a second recovery tank located downstream of said first collection tank .

Other embodiments of the process according to the invention are indicated in the appended claims.

The invention also relates to a device for selective separation of a granular material comprising a fraction of solid particles and a fraction of fine particles, said device comprising a feed of said granular material, a rotary member, a first collection zone of said solid particle fraction and a second collection zone of said separated fine particle fraction, characterized in that said rotary member is a rotatable circular plate having a bottom inclined with respect to a horizontal plane and a circumferentially extending edge flared upwardly therefrom, said second collection zone of said fine particle fraction being located in a central zone of said rotating circular plate.

Such a device for separating a granular material comprising massive particles (filiform + coarse) and fine particles advantageously makes it possible to avoid any clogging related to the presence of filiform particles, the separation not requiring the use of elements provided with fibers or bristles or with the use of screens but with a rotating circular plate having a bottom inclined with respect to a horizontal plane and a peripheral edge flaring upwardly from this bottom. In addition, this device allows selective separation, said filiform elements agglomerated in the form of balls and the coarse particles being recovered at the periphery of said rotary plate while said fine particles are concentrated at the center of said rotary plate in said collection zone of said fine particles. .

Advantageously, according to the device of the present invention, said fraction of solid particles comprises filiform particles and / or coarse particles.

Preferably, according to the device of the present invention, said rotary circular plate has four quadrants, a first quadrant extending from 0 to 90 °, a second quadrant extending, in a trigonometric marker, from 90 ° to 180 ° and a third quadrant extending from 180 ° to 270 ° with respect to a point 0 corresponding to an uppermost point of said rotating circular plate when said latter is at a standstill, said first collection zone of said massive particles being a ramp descending fixed along at least a portion of said third quadrant of said rotating circular plate, preferably along an arc of between 180 ° and 270 °.

Advantageously, according to the device of the present invention, said second collection zone of said fine particles comprises at least one opening made on the bottom of said central collection zone or a worm.

Equally advantageous, according to the device of the present invention, said descending ramp is extended by a finger screen ensuring a separation between said filiform particles agglomerated in the form of balls and said coarse particles.

Other embodiments of the granular material separation device according to the invention are indicated in the appended claims.

The invention further relates to the use of the device for the selective separation of the bulk particle fraction from the fine particle fraction of a granular material.

Other forms of use of the granular material separating device according to the invention are indicated in the appended claims.

Other features, details and advantages of the invention will become apparent from the description given below, without limitation and with reference to the accompanying drawings.

Figure 1 illustrates an embodiment of the device for separating a granular material according to the invention.

FIG. 2 illustrates another embodiment of the device for separating a granular material according to the invention.

Figure 3 is a side view of the separating device of a granular material according to the invention.

In the figures, identical or similar elements bear the same references.

Figure 1 illustrates an embodiment of the device for separating a granular material according to the invention. The granular material comprising filiform particles (1), fine particles (2) and coarse particles (3) is introduced into the rotating circular plate (5) via a feed ramp (4). The rotating circular plate (5) is inclined at an angle α (shown in Fig. 3) with respect to a horizontal plane and rotates about a central axis (6) clockwise (direction indicated by the arrow) at a a rotational speed of at least 50% but less than 100% of the critical rotational speed of said rotating circular plate (5) so that movements of the material according to the cascade regimes (displacement illustrated by the large dashes) and cataract (displacement shown by the small dashes) are obtained simultaneously.

The fine particles (2) are subjected to the cataract regime and describe trajectories passing through the central collection zone (7) where they accumulate.

The filiform particles (1) and the coarse particles (3) are subjected to the cascade regime which causes a drop of the massive particles (filiform + coarse) on each other. This has the effect that the filiform particles (1) collide with each other and form balls (8) entangled. The filiform particles in the form of balls (8) as well as the coarse particles (3) float on the surface of the granular material fed and are recovered by overflow above the peripheral edge (9) of the rotating circular plate (5), following their driving down by the force of gravity, in a peripheral collector (10). The fine particles (2) are concentrated at the bottom of the rotating circular plate (5) in the central collection zone (7) and are recovered by flow via openings (11) made in said central collection zone (7). near said axis of rotation (6). Said peripheral collector (10) is extended by a finger screen (12) allowing the coarse particles (3) sliding along said peripheral collector (10) to fall into a first collection tank (13) through the fingers of said screen. fingers (12). The filiform particles in the form of balls (8) slide on the finger screen (12) before being collected in a second recovery tank (14).

FIG. 2 illustrates another embodiment of the device for separating a granular material according to the invention and is identical to FIG. 1 except that an endless screw (15) ensures the recovery of the fine particles (2). ) concentrated at the bottom of the rotating circular plate (5) in the central collection area (7) near said axis of rotation (6). In addition, according to this embodiment, a deflector (16) directs the fine particles (2) towards the central collection zone (7) where an end of said worm (15) is arranged to extract said fine particles (2). ) agglomerated in said central collection area (7).

Figure 3 is a side view of the separating device of a granular material according to the invention which is illustrated the angle of inclination (a) of the rotating circular plate (5).

Examples

A residue of grinding of waste electrical and electronic equipment, previously subjected to a first separation, for example magnetic or by eddy current, is introduced on a rotating circular plate having a diameter of 1 m, a peripheral edge of a height 15 cm (overflow height) and a central deflector.

The grinding residue introduced on the plate comprises filiform particles (for example sheathed or unsheathed electrical wires), massive particles (coarse) of plastic and metal and fine particles (mineral fraction).

Several particle size separation tests were carried out by varying, as indicated in the table below, the following parameters: the inclination of the rotating circular plate at an angle with respect to a horizontal plane; feeding the grinding residue onto the inclined rotating circular plate, - the mass of the treated grinding residue, - the quantities (%) of solid particles and fine particles constituting the grinding residue, - the quantities (%) of solid particles having a size greater than 5 mm and the quantities (%) of fine particles having a size of less than 5 mm, - the rotational speed of the inclined rotating circular plate and, therefore, the% of the critical rotation speed of the rotating circular plate inclined.

All these tests made it possible to achieve a satisfactory selective particle size separation, the massive particles being displaced in a cascade regime towards the periphery of the inclined rotating circular plate, the fine particles being displaced towards a central collection zone of the rotating circular plate inclined according to a cataract regime and the filiform particles aggregating together in the form of pellets on the surface of the grinding residue. The massive particles as well as the filiform particles agglomerated in the form of balls were recovered, by overflow of the circular plate, in a peripheral collector before being separated from each other by passage on a finger screen. Fine particles were recovered in the center of the rotating circular plate, either through an opening on the bottom of the central collection area, or using a worm.

Optimum separation, however, was obtained by applying the parameters of Test No. 4, where it was shown that a longer duration of treatment of the grinding residue made it possible to increase by approximately 30% the feed rate of the feed. the granular material on the inclined rotating circular plate without reducing the quality of the separation obtained.

It is understood that the present invention is in no way limited to the embodiments described above and that many modifications can be made without departing from the scope of the appended claims.

Claims (11)

A method of selectively separating a granular material comprising a bulk particle fraction and a fine particle fraction to separate said bulk particle fraction from said fine particle fraction, said method comprising a step of feeding said granular material, a step of selectively separating said fraction of solid particles from said fraction of fine particles and a step of recovering said fraction of separated solid particles and said fraction of separated fine particles, characterized in that said feeding of said granular material is performed on a rotating circular plate having a bottom inclined with respect to a horizontal plane and a central zone for collecting said fine particles, said method furthermore simultaneously comprising a first displacement of said solid particles in a cascade regime towards a periphery of said plate rotating a second displacement of said fine particles in a cataract regime towards said central collecting zone of said rotating circular plate, by rotation of said rotating circular plate at a rotation speed of at least 50% but less than 100% of the speed; critical of rotation of said rotating circular plate, with said separation of said solid particle fraction from said fine particle fraction and said recovery of said massive particle fraction by overflow of said rotating circular plate and said fraction of fine particles separated and concentrated in said central collection zone of said rotating circular plate. 2. Process for the selective separation of a granular material according to claim 1, characterized in that said fraction of solid particles comprises filiform particles and / or coarse particles. 3. A method of selective separation of a granular material according to claim 2, characterized in that said rotary circular plate has, in a trigonometric reference, a first quadrant extending from 0 to 90 °, a second quadrant extending from 90 ° to 180 ° and a third quadrant extending from 180 ° to 270 ° with respect to a point 0 corresponding to an uppermost point of said rotating circular plate when it is stopped and in that said particles filiforms and / or said coarse particles are recovered in a peripheral collector in the form of a fixed descending ramp along at least a portion of said third quadrant of said rotary circular plate, preferably along an arc of between 180 ° and 270 °, after their overflow of said rotating circular plate, said filiform particles agglomerating them in the form of balls. 4. A method of selective separation of a granular material according to any one of claims 1 to 3, characterized in that said recovery of said fine particles in said central collection zone of said inclined rotating circular plate is performed manually, preferably by suction , preferably via at least one opening made on the bottom of said central collection zone, preferably with the aid of a worm. 5. A method of selective separation of granular material according to claim 3 or claim 4, characterized in that a separation of said coarse particles of said filiform particles agglomerated in the form of balls is carried out by means of a finger screen located in the extension. said peripheral collector. 6. Apparatus for selective separation of a granular material comprising a fraction of solid particles and a fraction of fine particles, said device comprising a feed of said granular material, a rotary element, a first zone for collecting said fraction of solid particles and a second collection zone of said fraction of separated fine particles, characterized in that said rotary member is a rotating circular plate having a bottom inclined with respect to a horizontal plane and a peripheral edge extending flared upwardly from of said bottom, said second collection zone of said fraction of fine particles being located in a central zone of said rotary circular plate. 7. Device for separating a granular material according to claim 6, characterized in that said fraction of solid particles comprises filiform particles and / or coarse particles. 8. Apparatus for selective separation of a granular material according to claims 6 and 7, characterized in that said rotary circular plate has four quadrants, a first quadrant extending from 0 to 90 °, a second quadrant extending, in a trigonometric marker, from 90 ° to 180 ° and a third quadrant extending from 180 ° to 270 ° with respect to a point 0 corresponding to an uppermost point of said rotating circular plate when it is stopped, said first collection zone of said solid particles being a fixed downward ramp along at least a portion of said third quadrant of said rotating circular plate, preferably along an arc of between 180 ° and 270 °. 9. Device for selective separation of a granular material according to any one of claims 6 to 8, characterized in that said second collection zone of said fine particles comprises at least one opening made on the bottom of said central collection zone or a worm. 10. Device for separating a granular material according to claim 8, characterized in that said downward ramp is extended by a finger screen ensuring a separation between said filiform particles agglomerated in the form of pellets and said coarse particles. 11. Use of the device according to any one of claims 6 to 10 for the separation of the bulk particle fraction of the fine particle fraction of a granular material.